Hi Yingzhen,
IP Flexible Algorithms are like SR Flexible Algorithms in the following
respects:
- Links have IGP metrics, TE metrics, delay metrics and administrative colors
- FADs define Flexible Algorithms
More specifically, the FAD:
- Indicates which metric type the Flexible Algorithm uses
- Specifies constraints in terms of link colors that are included or excluded
from the Flexible Algorithm.
The significant difference between IP Flexible Algorithms and SR Flexible
Algorithms is:
- SR Flexible Algorithms bind FADs to prefix SIDs or SRv6 locators
- IP Flexible Algorithms bind FADs to IPv4 or IPv6 addresses.
So, IP Flexible Algorithms can be deployed in any IP network, even in the
absence of SR.
Ron
Juniper Business Use Only
-----Original Message-----
From: Yingzhen Qu <yingzhen...@futurewei.com>
Sent: Saturday, October 3, 2020 2:08 PM
To: Peter Psenak <ppse...@cisco.com>; Gyan Mishra <hayabusa...@gmail.com>; Ron
Bonica <rbon...@juniper.net>
Cc: lsr@ietf.org; Jeff Tantsura <jefftant.i...@gmail.com>
Subject: Re: [Lsr] FW: New Version Notification for
draft-bonica-lsr-ip-flexalgo-00.txt
[External Email. Be cautious of content]
Hi Peter,
Using flex-algo, a SRv6 locator can be associated with a single algo, which
means an IPv6 or IPv4 address can also be associated with a single algo. So my
understanding is Ron's proposal is making the configuration of flex-algo
easier? Instead of using the exclude or include list you can configure a
loopback address to a flex-algo directly?
Thanks,
Yingzhen
On 10/3/20, 2:47 AM, "Peter Psenak" <ppse...@cisco.com> wrote:
Hi Yingzhen,
On 02/10/2020 22:15, Yingzhen Qu wrote:
> Hi Peter,
>
> My understanding of flex-algo is that for traffic destined to a prefix on
a particular algo, it can only be routed on routers belong to that algo, which
also means only routers in that algo calculates how to reach that prefix and
install it into the routing table. It seems to me that using flex-algo (section
12 of the draft) it's possible to have a loopback address associated with only
one algo, please correct me if I'm missing or misunderstood something.
you are right. That is exactly what is being done for flex-algo with
SRv6 - locator is associated with a single algo only. The proposal uses
the same concept.
thanks,
Peter
>
> Thanks,
> Yingzhen
>
> On 10/2/20, 9:43 AM, "Lsr on behalf of Peter Psenak"
<lsr-boun...@ietf.org on behalf of ppsenak=40cisco....@dmarc.ietf.org> wrote:
>
> Gyan,
>
> On 02/10/2020 18:30, Gyan Mishra wrote:
> > All,
> >
> > With SRv6 and IP based flex algo a generic question as it applies
to
> > both. Is it possible to have within a single IGP domain different
sets
> > of nodes or segments of the network running different algorithms.
>
> absolutely.
>
> > From
> > both drafts it sounds like all nodes have to agree on same
algorithm
> > similar to concept of metric and reference bandwidth all have to
have
> > the same style metric and play to the same sheet of music.
>
> all participating nodes need to agree on the definition of the
flex-algo
> and advertise the participation. That's it.
>
> > If there was
> > a way to use multiple algorithms simultaneously based on SFC or
services
> > and instantiation of specific algorithm based on service to be
> > rendered. Doing so without causing a routing loop or sub optimal
> > routing.
>
> you can certainly use multiple algorithms simultaneously and use algo
> specific paths to forward specific traffic over it. How that is done
> from the forwarding perspective depends in which forwarding plane you
> use. Flex-algo control plane is independent of the forwarding plane.
>
>
> >I thought with flex algo that there exists a feature that on
> > each hop there is a way to specify which algo to use hop by hop
similar
> > to a hop by hop policy based routing.
>
> no, there is no hop-by-hop classification, that is problematic and
does
> not scale for high speeds. Classification is done at the ingress
only.
>
> thanks,
> Peter
>
> >
>
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